The surface of the eyes contains antibacterial agents in tears and secretions that kill potential pathogens.

“on the surface of your eyes those corneas the shiny part of your eyes on the outside there are a bunch of different chemical features there are tears that are made by your lacrimal glands but there also a lot of antibacterial agents that actively kill off stuff that could potentially infect your body... if you've ever woken up in the morning and you have some crust on your eyes and you look at that crust that kind of yellowy stuff sometimes it's yellow I know this is kind of gross that's actually dead bacteria that your eyes have successfully defeated during your night's sleep”